Figure 1
Teaching Case
SectionChest imaging
Case TypeClinical Cases
AuthorsVermeiren L, De Wever W
Connected authors
62 years, female
A 62-year-old woman was referred to the department of pneumology for further work-up of pulmonary hypertension with dyspnoea. Chest radiograph showed a translucent right lung due to oligaemia.
Acute pulmonary embolism – Westermark sign.
A 62-year-old woman was referred to the department of pneumology for a further work-up of pulmonary hypertension with dyspnoea NYHA stage III (= marked limitation of physical activity).
She had a history of pulmonary embolism with right sided heart failure two years ago.
Laboratory findings revealed a decreased protein S, protein C and factor II.
A chest radiograph showed an increased translucency and a reduction of vascular markings in the right lung (Fig. 1).
Contrast enhanced CT of the chest revealed a clot in the right pulmonary artery with extension into its branches (Fig. 2) and an eccentric mural thrombus in the segmental branch of the left lower lobe (Fig. 3). Mosaic perfusion is seen bilaterally (Fig. 4). The truncus pulmonalis and pulmonary arteries are enlarged.
A pulmonary angiography was performed, which showed a complete obstruction of the right pulmonary artery. There is no perfusion in the entire right lung, with sparing of the apicoposterior segmental artery (Fig. 5A). On the left side, the angiogram demonstrates a filling defect in the segmental branch of the left lower lobe and of the lingula with hypo-perfusion of the lower left lobe (Fig. 5B). The angiogram also confirms enlarged pulmonary arteries.
She had a history of pulmonary embolism with right sided heart failure two years ago.
Laboratory findings revealed a decreased protein S, protein C and factor II.
A chest radiograph showed an increased translucency and a reduction of vascular markings in the right lung (Fig. 1).
Contrast enhanced CT of the chest revealed a clot in the right pulmonary artery with extension into its branches (Fig. 2) and an eccentric mural thrombus in the segmental branch of the left lower lobe (Fig. 3). Mosaic perfusion is seen bilaterally (Fig. 4). The truncus pulmonalis and pulmonary arteries are enlarged.
A pulmonary angiography was performed, which showed a complete obstruction of the right pulmonary artery. There is no perfusion in the entire right lung, with sparing of the apicoposterior segmental artery (Fig. 5A). On the left side, the angiogram demonstrates a filling defect in the segmental branch of the left lower lobe and of the lingula with hypo-perfusion of the lower left lobe (Fig. 5B). The angiogram also confirms enlarged pulmonary arteries.
Images are compatible with acute pulmonary embolism of the right pulmonary artery and chronic pulmonary embolism in the left lower pulmonary artery. A right sided cardiac catheterisation showed a moderate pulmonary arterial hypertension, which confirmed the diagnosis of chronic pulmonary embolism in the left lower pulmonary artery.
The chest radiograph showed an oligaemic right lung, also known as Westermark’s sign. The Westermark sign is an eponym indicating oligemia distal to a large central pulmonary embolus, which causes an obstruction of blood flow more distally. Presumably the lack of flow to these more distal vessels results in the radiographic transparency. The Westermark sign has a low sensitivity (14%) but a high specitivity (92%) [1]. The differential diagnosis of a hyperlucent lung region includes pneumothorax, presence of a huge bulla or hypoperfusion due to small airways disease.
Other radiological signs of pulmonary embolism on conventional radiography can be a peripheral, wedge-shaped consolidation with the lung base on the pleural surface (Hampton’s hump), enlarged pulmonary arteries (Fleischner sign), a small pleural effusion or elevation of the ipsilateral diaphragm. The chest radiograph may also be normal.
The hypo-perfusion of the left lower lobe is caused by chronic pulmonary embolism. The enlarged pulmonary arteries are due to chronic pulmonary hypertension secondary to chronic thromboembolism.
Laboratory findings suggested protein S deficiency. Protein S deficiency is associated with a hypercoagulable state and an increased risk of venous thrombosis and pulmonary embolism. As a treatment, a vena cava filter placement was performed and anti-coagulation was started.
DIFFERENTIAL DIAGNOSIS
1) Bulla due to emphysema
2) Pneumothorax
3) Hypoperfusion due to small airway disease
The chest radiograph showed an oligaemic right lung, also known as Westermark’s sign. The Westermark sign is an eponym indicating oligemia distal to a large central pulmonary embolus, which causes an obstruction of blood flow more distally. Presumably the lack of flow to these more distal vessels results in the radiographic transparency. The Westermark sign has a low sensitivity (14%) but a high specitivity (92%) [1]. The differential diagnosis of a hyperlucent lung region includes pneumothorax, presence of a huge bulla or hypoperfusion due to small airways disease.
Other radiological signs of pulmonary embolism on conventional radiography can be a peripheral, wedge-shaped consolidation with the lung base on the pleural surface (Hampton’s hump), enlarged pulmonary arteries (Fleischner sign), a small pleural effusion or elevation of the ipsilateral diaphragm. The chest radiograph may also be normal.
The hypo-perfusion of the left lower lobe is caused by chronic pulmonary embolism. The enlarged pulmonary arteries are due to chronic pulmonary hypertension secondary to chronic thromboembolism.
Laboratory findings suggested protein S deficiency. Protein S deficiency is associated with a hypercoagulable state and an increased risk of venous thrombosis and pulmonary embolism. As a treatment, a vena cava filter placement was performed and anti-coagulation was started.
DIFFERENTIAL DIAGNOSIS
1) Bulla due to emphysema
2) Pneumothorax
3) Hypoperfusion due to small airway disease
References
[1] Worsley DF, Alavi A, Aronchick JM et al (1993) Chest radiographic findings in patients with acute pulmonary embolism: observations from the PIOPED Study. Radiology 189:133-6 (PMID: 8372182)
Case information
| URL: | https://www.eurorad.org/case/8817 |
| DOI: | 10.1594/EURORAD/CASE.8817 |
| ISSN: | 1563-4086 |
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